The science of the scoop: new research in ice cream making
cream stay smooth and creamy during long periods in the freezer,
suggests new research by food scientist Douglas Goff of the
University of Guelph, in Canada.
Ice-modifying proteins extracted from winter wheat may help ice cream stay smooth and creamy during long periods in the freezer, suggests new research by food scientist Douglas Goff of the University of Guelph, in Canada.
Goff presented his research, along with other ice cream experts, at a session on "The Science of Ice Cream," at the American Association for the Advancement of Science (AAAS) Annual Meeting.
Goff and his colleagues are investigating new ways to improve ice cream quality by introducing new ingredients and manipulating its structure. They have examined certain proteins in winter wheat, which help the plant survive winter by modifying the growth of cell-damaging ice crystals.
The study was done in collaboration with Ice Biotech, who developed and patented the proteins. Goff said that using these proteins in ice cream production has made some "really smooth" batches of ice cream. He plans to propose new processes in ice cream manufacture to dairy industry officials.
Ice cream gets its creamy texture from the way that fat molecules, air bubbles and ice crystals are assembled within a highly concentrated mixture of sugar-water. Getting this assemblage right is no easy task, according to Goff, who uses electron microscopy to zoom in on ice cream's molecular makeup.
"Ice cream is a very complex product to manufacture, especially since the industry has changed considerably over the last couple of decades," Goff said. "You can make a very good gallon of ice cream in the kitchen without knowing anything about the science [of the process]. But, if you're trying to send ice cream around the world and make it last, so that the person who eats it gets a smooth product, there is a lot to learn."
Goff's microscopy images of ice cream reveal a matrix of tiny fat globules, surrounding air bubbles and ice crystals. Ice cream is an emulsion - like oil and vinegar salad dressing - so the matrix of fat particles must be stabilised by milk proteins to prevent the fat from clumping together. The other component of the emulsion is a solution of sugar-water, from which the ice crystals form during freezing. The solution never freezes completely, allowing ice cream to be scooped and chewed at freezer temperatures.
The process of manufacturing ice cream is a science unto itself, according to Bob Roberts of Pennsylvania State University. When the ingredients are blended together, they form an "ice cream mix," but turning ice cream mix into the beloved frozen dessert is more complicated than one might think.
"You've got gas, liquids, and solids, and as the temperature changes, then so do the volumes of each phase. So it's a tough system. On the other hand, it works, and people are able to make it," Roberts said.
He and his colleagues are investigating possible ways to improve ice cream consistency through manufacturing. For example, they have narrowed down the range of possible mixing speeds during the freezing process that would produce the ideal ice crystal size.
"The manufacturing system is constantly under study," Roberts said.
Ice cream culture has also changed with the times, according to food anthropologist Merry White of Boston University. Recently, ice cream has been adopted by many cultures around the world. Thus it's possible to eat gelato, in China for example, and be eating a Chinese dessert, according to White. She calls this phenomenon "glocalisation," as foods lose their initial local identities and get reassigned new ones.
"Ice cream reveals a great way of looking at how foods change. We think ice cream is all-American, but you really have to look further," she said.
